Certain groups of people may have twice the risk of dying from a heart attack during heat waves and high levels of fine particulate pollution, according to a new study published in Circulation, the journal of the American Heart Association (AHA).

Researchers analyzed the specifics of over 202,000 heart attacks that occurred in the Chinese province of Jiangsu between the years 2015-2020.

They found that days with "extreme heat, extreme cold or high levels of fine particulate matter air pollution" were linked to a higher risk of death from cardiac events.

("Fine particulate matter" refers to particles that are 2.5 microns or fewer in diameter.)

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The study focused on Jiangsu, since the region experiences a wide range of temperatures and fine particulate pollution levels, a press release from AHA said.

To determine when a heat wave was occurring, the researchers used the daily heat index, which measures a combination of heat and humidity.

The death risk was twice as high during four-day heat waves that had fine particulate pollution above 37.5 micrograms per cubic meter, per the study findings. 

The risk was highest among women and older adults.

Among the adults who died from heart attacks, the average age of death was 77.6, with 52% of the those who passed older than age 80.

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"Extreme temperature events are becoming more frequent, longer and more intense, and their adverse health effects have drawn growing concern," said senior author Yuewei Liu, M.D., PhD, an associate professor of epidemiology in the School of Public Health at Sun Yat-sen University in Guangzhou, China, in the press release.

"Another environmental issue worldwide is the presence of fine particulate matter in the air, which may interact synergistically with extreme temperatures to adversely affect cardiovascular health," he continued.

"However, it remains unknown if and how co-exposure to extreme temperatures and fine particulate pollution might interact to trigger a greater risk of death from heart attack, which is an acute response potentially brought on by an acute scenario and a great public health challenge due to its substantial disease burden worldwide."

Dr. Alexander Postalian, a cardiologist at The Texas Heart Institute, was not part of the research but said the findings are in line with what he has observed.

"Exposure to extreme heat not only increases individuals’ risk for heat exhaustion and heat stroke, but it also puts stress on their cardiovascular systems, making their hearts work harder," he told Fox News Digital. 

"This increased exertion can raise the risk of heart attacks or heart failure."

The combination of extreme heat and extreme pollution is the "perfect storm," Postalian said — causing stress for an individual’s cardiovascular system. 

"Exposure to either of these situations increases the risk of heart attacks and heart issues," he said. 

To help prevent the risk of death from heart attack, the study researchers recommended reducing exposure to both extreme temperatures and fine particulate pollution.

"Strategies for individuals to avoid negative health effects from extreme temperatures include following weather forecasts, staying inside when temperatures are extreme, using fans and air conditioners during hot weather, dressing appropriately for the weather, proper hydration and installing window blinds to reduce indoor temperatures," said Liu in the release. 

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"Using an air purifier in the house, wearing a mask outdoors, staying clear of busy highways when walking and choosing less strenuous outdoor activities may also help to reduce exposure to air pollution on days with high levels of fine particulate pollution," he added.

Individuals with a history of heart disease or other significant cardiovascular problems should watch for chest pain or shortness of breath, take shorter walks outside and limit total time spent outside during extreme heat conditions, Postalian recommended.

"Some medications, such as diuretics, can increase the likelihood of developing dehydration," the cardiologist added.

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"Dehydration can cause a drop in blood pressure, creating feelings of lightheadedness, thereby increasing the risk of injuries from falls — and it also can affect one’s kidney function," he continued. 

"All individuals should drink plenty of fluids to avoid dehydration."

People taking cardiovascular medications or suffering from heart disease should avoid spending prolonged time in temperatures above 100 degrees, and should talk to their doctors about ways to protect themselves from extreme weather conditions, Postalian added.